Resin-coated copper foil for multilayer printed wiring board and multilayer printed wiring board provided with said copper foil

ABSTRACT

PCT No. PCT/JP95/01335 Sec. 371 Date Dec. 31, 1997 Sec. 102(e) Date Dec. 31, 1997 PCT Filed Jul. 4, 1995 PCT Pub. No. WO97/02728 PCT Pub. Date Jan. 23, 1997A resin-coated copper foil for use in a multilayer printed wiring board, characterized by having on one surface thereof a resin composition comprising, based on the total amount of the resin components, 50 to 90% by weight of epoxy resins, 5 to 20% by weight of a polyvinyl acetal resin, and 0.1 to 20% by weight of an urethane resin, with the proviso that 0.5 to 40% by weight of the epoxy resins is a rubber-modified epoxy resin; and a multilayer printed wiring board using the resin-coated copper foil therein.

RELATED APPLICATION

This application is an application under 35 U.S.C. §371 ofPCT/JP95/01335, filed Jul. 4, 1995.

TECHNICAL FIELD

The present invention relates to a resin-coated copper foil for use in amultilayer printed wiring board and a multilayer printed wiring boardusing the copper foil(s) therein. It is noted that the presentspecification illustrates a multilayer printed wiring board having 2inner layer circuits and 2 outer layer circuit.

BACKGROUND ART

In most cases, a laminate for producing therefrom a printed wiring boardused in the electronic industry is manufactured by impregnating a glasscloth, kraft paper, a glass nonwoven fabric or the like with athermosetting resin such as phenolic resin or epoxy resin, setting thethermosetting resin semi-cured to produce a prepreg with the semi-curedresin attached thereto, and laminating a copper foil on one or each ofboth surfaces of the prepreg to obtain a copper-clad laminate.

Further, a multilayer printed wiring board having two inner-layercircuits and two outer-layer circuits is produced as illustrated below.

The one or two surface copper foils of the aforementioned copper-cladlaminate are subjected to etching or the lie for formation of one or twoinner-layer circuits to produce an inner-layer member comprising theinner-layer substrate (prepreg) and the one or two inner-layer circuits.Separately, the same prepreg as mentioned above has a copper foilattached to one or both surfaces thereof and is then subjected toetching or the like to produce an outer-layer member comprising theouter-layer substrate (prepreg) and outer-layer copper foil circuit. Twosuch outer-layer members sandwich said inner-layer member intherebetween, after which these three members are heated under apressure to produce a multilayer printed wiring board having twoinner-layer circuits and two outer-layer circuits.

The laminate produced by the aforementioned manufacturing method haspractically satisfactory heat resistance, electrical properties andchemical resistance for use as a material or blank for a printed wiringboard.

However, the use of the prepreg as described above raises problems,examples of which are an uneven surface called a "glass fiber texture"formed on the surface(s) of the laminate after pressing thereof, thelowering of insulation reliability called "migration", and a difficultyin perforating the laminate with a laser beam because of the inclusionin the prepregs, between the inner layer circuit and outer-layercircuit, of glass fibers which can not be decomposed even at a hightemperature.

In attempts to overcome these problems, there have hitherto beenproposed methods for producing a multilayer printed wiring board withoutuse of any prepreg between inner-layer circuit and outer-layer circuit."Printed Circuit World Convention VI, I9" describes a method forproducing a multilayer printed wiring board with use of resin-coatedcopper foils respectively having a plurality of resin layers which aredifferent in cured state and covered with a protective film. However,this method raises problems as to disadvantageously complicatedproduction steps due to application of resin layers differing in curedstate onto the surface of copper foils, troublesome peeling of theprotective films and costly use of the protective film.

The inventors of the present invention have already proposed an adhesivefor copper foils which is useful for laminating a copper foil on asubstrate such as a metal plate or a plastics plate, and also proposedon adhesive-coated copper foil (Japanese Patent Application No.243,430/94). The adhesive and the adhesive-coated copper foil disclosedherein are designed to adhere to a material under lower pressure andtemperature than conventional ones. However, they are not intended to beused for press lamination or multilayer relamination because aninsulation layer of variable thickness would result and there would behigh resin flow causing excessive resin "bleed out". Another problem isa so-called "blocking phenomenon" that is adhesion between the resinsurface of one copper foil and the glossy surface of another copper foiladjacent to said one copper foil when the resin-coated copper foils arestacked one upon another for storage.

Further, Japanese Patent Application No. 22,321/95 has proposed anadhesive composition to achieve the low resin flow even during the presslamination. The resin composition disclosed in the above Applicationcomprises 20 to 50 wt/%, based on the total amount of the resincomponents, of a polyvinyl acetal resin thereby to control the resinflow during the course of press molding. The intention of this inventionis to produce a printed wiring board while eliminating the conventionalcopper foil roughening step. However, there may be defects such as voidsin the inner layer circuits after relamination. Furthermore, since amalamine resin is constituent of the adhesive it may be attached byetching solution during subsequent processing.

In Japanese Patent Laid-Open Gazette No. 106,752/95, the inventors ofthe present invention have pointed out or indicated problems which willbe raised as to the use of a melamine resin as an adhesive for use in aprinted wiring board. According to this specification the inclusion ofmelamine resin in the adhesive used to coat copper foil for printedwiring board applications results in chemical attack by copperchloride/hydrochloric acid etching solutions. This will raise a problemthat copper ions remain on the surfaces of the substrate even if theetched copper foils are washed with water and these copper ions inhibitthe cure of a solder resist ink applied on the surfaces of the substratethereby lowering the adhesion of the ink to the substrate. Since themelamine resin is disclosed to be used as part of the resin compositionin Japanese Patent Application No. 22,321/95 as well, it is difficult toobviate the foregoing problem.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a resin-coated copperfoil for use in a multilayer printed wiring board, in which the resin isexcellently easy to handle due to its excellent blocking resistance andflexibility, and one which exhibits low resin flow during presslamination.

Another object of the present invention is to provide a multilayerprinted wiring board which is excellent in etching solution resistance,relamination integrity, surface smoothness and insulation reliabilityand easily perforated with a laser beam.

The resin-coated copper foil of the present invention for use in amultilayer printed wiring board, which foil is indispensable to attainthe above-mentioned objects, comprises on one surface thereof a resincomposition comprising, based on the total amount of the resincomponents, 50 to 90% by weight of an epoxy resin, 5 to 20% by weight ofa polyvinyl acetal resin and 0.1 to 20% by weight of a urethane resin,with the proviso that 0.5 to 40% by weight of said epoxy resin is arubber-modified epoxy resin.

A detailed description will now be made of a resin-coated copper foilfor use in a multilayer printed wiring board of the present invention.

Commercially available epoxy resins for use in forming of laminates andelectronic parts can be used without any particular limitation as theepoxy resins for use in the resin composition used in the presentinvention. Examples of the epoxy resins are bisphenol A-type epoxyresins, bisphenol F-type epoxy resins, novolak epoxy resins, o-cresylicnovolak epoxy resins, triglycidyl isocyanurate, glycidylamine compoundssuch as N,N-diglycidylaniline, glycidyl ester compounds such asdiglycidyl tetrhydrophthalate, and brominated epoxy resins such astetrabromobisphenol A. In addition, there can also be used so-calledrubber-modified epoxy resins obtained as reaction products of a carboxylgroup-containing rubber with an epoxy resin, and epoxidizedpolybutadiene. These epoxy resins may be used either alone or inmixture. The degree of polymerization and epoxy equivalent of each ofthese epoxy resins are not particularly limited.

Preferable curing agents for the epoxy resins include generally knownlatent curing agents such as dicyandiamide, organic hydrazides,imidazoles, and phenolic novolak resins hardly curable at ambienttemperatures. The optimum amount of such a curing agent added to aparticular epoxy resin is known, but the amount thereof added mayarbitrarily be varied. These curing agents may be used either alone orjointly, and may preferably be used in combination with an epoxy resincuring accelerator such as a tertiary amine.

In the present invention, the epoxy resin content of the resincomposition is 50 to 90% by weight of the total amount of the resiningredients. When the content is lower than 50% by weight, the resultingprinted wiring board has inferior electrical properties and heatresistance. On the other hand, when it exceeds 90% by weight, the resinlayers become brittle and present handling difficulties.

The polyvinyl acetal resin for use in the resin composition used in thepresent invention may be a resin synthesized by the reaction ofpolyvinyl alcohol with an aldehyde. Reaction products of polyvinylalcohol having a variety of degrees of polymerization with a singlealdehyde or at least 2 kinds of aldehydes are now commercially availableas polyvinyl acetal resins for use in coatings and adhesives. They canbe used in the present invention without any particular limitation onthe kind of aldehyde and the degree of acetalization. In addition,although the degree of polymerization of polyvinyl alcohol as a rawmaterial is not particularly limited, products synthesized frompolyvinyl alcohol having a polymerization degree of 1,700 to 3,500 maydesirably be used in consideration of the heat resistance and solubilityin a solvent of the resulting resin. Furthermore, modified polyvinylacetal resins having carboxyl groups or the like introduced into themolecule are also commercially available and they can be used withoutany particularly limitation, as far as their compatibility with theepoxy resins to be used in combination is kept satisfactory.

In the present invention, the polyvinyl acetal resin content of theresin composition is 5 to 20% by weight of the total amount of the resiningredients of the resin composition. When it is lower than 5% byweight, controlled resin flow can not be achieved. On the other hand,when it exceeds 20% by weight, relamination becomes more difficult.

The urethane resins used in the resin composition according to used thepresent invention may be commercially available resins containingisocyanate groups in the molecule which are useful in adhesives andcoatings. The urethane resins used herein include reaction products of apolyisocyanate compound such as tolylene diisocyanate, diphenylmethanediisocyanate or polymethylenepolyphenyl polyisocyanate with a polyolsuch as trimethylolpropane, a polyether polyol or a polyester polyol.Since such compounds are so high in reactivity for resins that they aresometimes polymerized with water in the atmosphere, these resins may bestabilized with phenol or an oxime to form urethane resins called"blocked isocyanates" for the purpose of preferable use of said resins(highly reactive compounds) in the present invention.

In the present invention, the urethane resin content of the resincomposition is 0.1 to 20% by weight based on the total amount of theresin components. When it is lower than 0.1% by weight, the resultingproduct will be deteriorated in blocking resistance, whereas when itexceeds 20% by weight, the adhesiveness of the resin to the copper foilwill be lowered.

In the present invention, as far as commercially availablerubber-modified epoxy resin products for use in adhesives and coatingscan be used without any particular limitation as the rubber-modifiedepoxy resin which is a part of the epoxy resins contained in the resincomposition. The rubber-modified epoxy resins include EPIXLON TSR-960(trade name, manufactured by Dainippon Ink & Chemicals, Incorporated),EPOTOHTO YR-102 (trade name, manufactured by Tohto Kasei Co., Ltd.),SUMIEPOXY ESC-500 (trade name, manufactured by Sumitomo Chemical Co.,Ltd.) and EPOMIK VSR 3531 (trade name, manufactured by MitsuiPetrochemical Industries, Ltd.). These rubber-modified epoxy resins maybe used alone or in mixture. The rubber-modified epoxy resin content ofthe resin composition used in the present invention is 0.5 to 40% byweight of the total amount of the epoxy resins. Use of therubber-modified epoxy resin remarkably improve the resin-coated copperfoil in flexibility. However, when the rubber-modified epoxy resincontent is lower than 0.5% by weight, the effect of improving theflexibility can not be achieved. On the other hand, when it exceeds 40%by weight, the cured resin will be lowered in heat resistance anddeteriorated in blocking resistance.

Besides the foregoing indispensable components, the resin compositionused in the present invention may further comprise a resin such as apolyester resin, a phenolic resin or a phenoxy resin, a nonfibrousinorganic filler represented by talc and aluminum hydroxide, a flameretardant such as antimony trioxide, and an additives such as adefoaming agent, a leveling agent and a coupling agent. They areeffective in improving the resin surface smoothness and the flameretardancy of the cured products, and in reducing the cost, etc.

In the present invention, the resin composition mentioned above isdissolved in a general-purpose solvent such as toluene or methyl ethylketone, applied onto one surface of a copper foil, and then heated toremove the solvent and partially cure (semicure) the resins to produce aresin-coated copper foil ready for use. In this step, the kind andamount of a solvent used are not particularly limited. The copper foilsfor use in combination with the resin composition may be either a rolledcopper foil or an electrodeposited copper foil each having a thicknessof preferably 9 to 100 μm, more preferably 12 to 35 μm. The manners ofroughening treatment and corrosion prevention treatment of the copperfoils for use in combination with the resin composition are notparticularly limited, and customary methods of such treatments can beadopted.

A multilayer printed wiring board is produced using the resin-coatedcopper foil produced according to the foregoing procedure. Theconditions of production in this step may be the same as in theproduction of a multilayer printed wiring board according to theconventional lamination process. More specifically, the above mentionedresin-coated copper foil is applied to one or both surfaces of a printedand etched inner layer which has been subjected to a copper rougheningtreatment to enhance the bonding to the adjoining resin coated surfacesof the foil during the next relamination step. The resulting laminate isthen subjected to etching formation of outer layer circuits,perforation, plating up etc. to obtain a finished multilayer printedwiring board.

EXAMPLES

The present invention will be better understood by the followingExamples and Comparison Examples.

Example 1

(Preparation of Resin-Coated Copper Foil)

Sixth (60) parts by weight of a bisphenol A-type epoxy resin (tradename: EPOMIK R-301, manufactured by Mitsui Petrochemical Industries,Ltd.), 20 parts by weight (corresponding to 25% by weight of all theepoxy resins) of a rubber-modified epoxy resin (trade name: PEOTOHTOYR-102, manufactured by Tohto Kasei Co., Ltd.), 10 parts by weight of apolyvinyl acetal resin (trade name: DENKA BUTYRAL 5000A, manufactured byDenki Kagaku Kogyo Kabushiki Kaisha), 10 parts by weight of a urethaneresin (trade name: CORONATE AP-Stable, manufactured by NipponPolyurethane Industry Co., Ltd.), 2 parts by weight of dicyandiamide(reagent) as an epoxy resin curing agent (added in the form of adimethylformamide solution thereof having a solid content of 25%), and0.5 parts by weight of a curing accelerator (trade name: CUREZOL 2E4MZ,manufactured by Shikoku Chemicals Corp.) were dissolved in methyl ethylketone to prepare a resin composition having a solids content of 45%.

The resin composition so prepared was applied onto the roughened surfaceof an electrodeposited copper foil having a thickness of 18 μm, driedwith air, and then heated at 150° C. for 7 minutes to obtain a semicuredresin-coated copper foil, the thickness of the resin layer of which was100 μm.

(Production of Multilayer Printed Wiring Board)

(1) Production of Inner-Layer Member

An electrodeposited copper foil having had one surface thereof subjectedto roughening treatment and having a thickness of 35 μm was laminated oneach of the surfaces of an inner-layer substrate comprising 8 sheets ofa commercially available 0.1 mm-thick glass-epoxy prepreg in such a wayas to make the roughened surface of the foil contact with the prepreg(inner layer substrate), and then pressed together for at a pressure of30 kgf/cm² and a temperature of 170° C. for 60 minutes to produce adouble-faced copper-clad laminate wherein both surfaces of the prepregwere each covered with a copper foil. Both surfaces of this laminatewere subjected to etching or the like to form inner-layer circuits.

(2) Production of Multilayer Printed Wiring Board

Both etched surfaces of the inner layer member produced in (1) abovewere washed in pure water and dried. Thereafter, 2 pieces of theresin-coated copper foil produced according to the aforementionedprocedure were laminated respectively on the surfaces of the inner-layermember in such a way as to make the resin layers of the resin-coatedcopper foils contact respectively with the inner-layer member, pressedtogether at a pressure of 30 kgf/cm² and a temperature of 170° C. for 60minutes, and then subjected to etching or the like for formation ofouter-layer circuits thereby to produce a multilayer printed wiringboard with 4-layer circuits (2 inner-layer circuits and 2 outer-layercircuits).

Example 2

Seventy (70) parts by weight (in terms of solid content) of a brominatedepoxy resin (trade name: D.E.R. 514-EK80, manufactured by Dow ChemicalJapan Limited), 10 parts by weight of an o-cresylic novolak epoxy resin(trade name: EOCN-104S, manufactured by Nippon Kayaku Co., Ltd.), 10parts by weight (corresponding to 12.5 wt. % of all the epoxy resins) ofa rubber-modified epoxy resin (trade name: EPOMIK VSR3531, manufacturedby Mitsui Petrochemical Industries, Ltd.), 5 parts by weight of apolyvinyl acetal resin (trade name: DENKA BUTYRAL 6000CG, manufacturedby Denki Kagaku Kogyo Kabushiki Kaisha), 5 parts by weight of a urethaneresin (trade name: DESOMOPHENE CT-Stable, manufactured by Sumitomo BayerUrethane Co., Ltd.), 2 parts by weight of dicyandiamide (reagent) as acuring agent for the epoxy resins (added in the form of adimethylformamide solution of the curing agent having a solid content of25%), and 0.5 parts by weight of a curing accelerator (trade name:CUREZOL 2E4MZ, manufactured by Shikoku Chemicals Corp.) were dissolvedin methyl ethyl ketone to prepare a resin composition having a solidscontent of 50%.

The resin composition so prepared was applied onto the roughened surfaceof a commercially available electrodeposited copper foil having athickness of 18 μm, dried with air and then heated at 150° C. for 7minutes to produce a semicured resin-coated copper foil, the thicknessof the resin layer of which was 100 μm. A multilayer printed wiringboard comprising 4-layer circuits (2 inner-layer circuits and 2outer-layer circuits) was produced according to substantially the sameprocedure as in Example 1.

Comparative Example 1

A resin composition having a solids content of 45% was prepared insubstantially the same manner as in Example 1 except that a melamineresin (trade name: U-VAN 20SB, manufactured by Mitsui Toatsu Chemicals,Inc.) was used instead of the urethane resin (trade name: CORONATEAP-Stable, manufactured by Nippon Polyurethane Industry Co., Ltd.) usedin Example 1.

The resin composition so prepared was coated on an 18 μm-thick copperfoil to form a 100 μm-thick resin layer on the copper foil. Further,this resin-coated copper foil was used in substantially the same manneras in Example 1 to produce a multilayer printed wiring board comprising4-layer circuits (2 inner-layer circuits and 2 outer-layer circuits).

Comparative Example 2

A resin composition was prepared in substantially the same manner as inExample 1 except that 25 parts by weight of a polyvinyl acetal resin(trade name: DENKA BUTYRAL 6000CG, manufacture by Denki Kagaku KogyoKabushiki Kaisha) having a solid content of 35% was substituted for 10parts by weight of the resin having a solid content of 45% used inExample 1.

The resin composition so prepared was coated on an 18 μm-thick copperfoil to form a 100 μm-thick resin layer thereon. Further, this resincoated copper foil was used in substantially the same manner as inExample 1 to produce a multilayer printed wiring board comprising4-layer circuits (2 inner-layer circuits and 2 outer-layer circuits).

Comparative Example 3

Seventy-seven (77) parts by weight (in terms of solid content) of abrominated epoxy resin (trade name: D.E.R. 514-EK80, manufactured by DowChemical Japan Limited), 15 parts by weight of an o-cresylic novolakepoxy resin (trade name: EOCN-104S, manufactured by Nippon Kayaku Co.,Ltd.), 3 parts by weight of a polyvinyl acetal resin (trade name: DENKABUTYRAL 6000CG, manufactured by Denki Kagaku Kogyo Kabushiki Kaisha), 2parts by weight of dicyandiamide (reagent) as an epoxy resin curingagent (added in the form of a dimethylformamide solution thereof havinga solid content of 25%), and 0.5 parts by weight of a curing accelerator(CUREZOL 2E4MZ, manufactured by Shikoku Chemicals Corp.) were dissolvedin methyl ethyl ketone to prepare a resin composition having a solidcontent of 60%.

The resin composition so prepared was applied onto the roughened surfaceof a commercially available electrodeposited copper foil having athickness of 35 μm, dried with air, and then heated at 150° C. for 7minutes to produce a resin-coated copper foil having a 100 μm-thickresin layer. A multilayer printed wiring board comprising 4-layercircuits (2 inner-layer circuits and 2 outer-layer circuits) wasproduced according to substantially the same procedure as in Example 1.

The resin-coated copper foils and multilayer printed wiring boardsproduced in Examples 1 and 2 and Comparative Examples 1 to 3 wereevaluated for the following items. The results are shown in Tables 1 and2.

(Resin-Coated Copper Foil)

(1) Blocking Resistance:

A 35 μm-thick electrolytic copper foil was cut into 10 cm×10 cm waspieces, while the present and comparative resin-coated copper foils wereeach cut into pieces of the some size as above. The piece of theresin-coated copper foil was superimposed on the piece of the resin-freecopper foil with the resin surface of the former contacting with theglossy surface of the latter. These pieces were then kept under a loadof 500 g for 48 hours in a thermohumidstat (oven) set at a temperatureof 30° C. and a humidity of 40%, after which they were withdrawn fromthe oven to judge whether or not the resin surface was adhered to theglossy surface.

◯: not adhered

x: adhered

(2) Flexibility: according to JIS K 5400, diameter of stem: 2 mm

◯: not cracked

x: cracked

(Multilayer Printed Wiring Board)

(1) Peel Strength in Ordinary State: 10 mm wide, according to JIS C 6481

(2) Peel Strength after Soldering Treatment: 10 mm wide, according toJIS C 6481

(3) Soldering Heat Resistance: according to JIS C 6481

(4) Relamination of Inner Layer Circuits: After removal of the wholeouter-layer copper foil by etching, whether or not there is arelamination defect such as a void is visually judged.

◯: good

x: poor

(5) Thickness of Insulating Layer: The thicknesses of the resin layerbefore and after pressing were actually measured.

(6) Etching Solution Resistance: After removal of the whole outer-layercopper foil by etching and washing of the etched portion with water,whether or not any copper remained on the surface of the substrate wasmeasured according to EPMA analysis.

◯: no copper detected

x: copper detected

                  TABLE 1                                                         ______________________________________                                        Properties of Resin-Coated Copper Foil                                        Ex. & Comp. Ex.                                                                             Blocking Resistance                                                                        Flexibility                                        ______________________________________                                        Ex. 1         ∘                                                                              ∘                                      Ex. 2         ∘                                                                              ∘                                      Comp. Ex. 1   x            ∘                                      Comp. Ex. 2   ∘                                                                              ∘                                      Comp. Ex. 3   ∘                                                                              x                                                  ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Properties of Multilayer Printed Wiring Board                                                                  Thickness                                            Peel                     of                                                   Strength                 Insulating                                           in                       Layer                                                Ordinary          Re-    before                                               State/   Soldering                                                                              lamination                                                                           Pressing/                                            after    Heat     of Inner                                                                             after  Etching                               Ex. and Soldering                                                                              Resistance                                                                             Layer  Pressing                                                                             Solution                              Comp. Ex.                                                                             (kgf/cm) (sec)    Circuits                                                                             (μm)                                                                              Resistance                            ______________________________________                                        Ex. 1   1.35/1.30                                                                              120<     ∘                                                                        100/95 ∘                         Ex. 2   1.41/1.41                                                                              120<     ∘                                                                        100/90 ∘                         Comp.Ex.1                                                                             1.32/1.20                                                                              120<     x      100/95 x                                     Comp.Ex.2                                                                             1.45/1.44                                                                              120<     x      100/95 ∘                         Comp.Ex.3                                                                             1.48/1.41                                                                              120<     ∘                                                                        100/60 ∘                         ______________________________________                                    

As is apparent from the results in Tables 1 and 2, Examples 1 and 2showed at least comparable or superior properties to those ofComparative Examples 1 to 3 in all the tests.

[Industrial Applicability]

The resin-coated copper foil of the present invention for use in amultilayer printed wiring board is excellent in handleability owing toexcellent blocking resistance and flexibility, and shows low resin flowduring the process of press lamination. Furthermore, the multilayerprinted wiring board of the present invention using this resin-coatedcopper foil therein is excellent in etching solution resistance,relamination integrity, surface smoothness and insulation reliability,and easily perforated with a laser beam.

What is claimed is:
 1. A resin-coated copper foil for use in amultilayer printed wiring board, which is characterized by having on onesurface thereof a composition comprising resins, wherein the resinsinclude 60 to 90% by weight of said resins of epoxy resins, 5 to 10% byweight of said resins of a polyvinyl acetal resin and 0.1 to 20% byweight of said resins of a urethane resin, with the proviso that 0.5 to40% by weight of the total amount of the epoxy resins is arubber-modified epoxy resin, with the composition being on a roughenedsurface of the copper foil.
 2. A resin-coated copper foil for use in amultilayer printed wiring board as claimed in claim 1, wherein saidresin composition is in a semicured state.
 3. A multilayer printedwiring board comprising a resin-coated copper foil as claimed in claim 1or
 2. 4. A resin-coated copper foil of claim 1, wherein said compositionfurther comprises a resin selected from the group consisting of apolyester resin, a phenolic resin, and a phenoxy resin.
 5. Aresin-coated copper foil of claim 1, wherein said composition furthercomprises a non-fibrous inorganic filler selected from the groupconsisting of talc and aluminum hydroxide.
 6. A resin-coated copper foilof claim 1, wherein said composition further comprises antimony trioxideas a flame retardant.
 7. A resin-coated copper foil of claim 1, whereinsaid composition further comprises an additive selected from the groupconsisting of a defoaming agent, a leveling agent, and a coupling agent.